It is well known in the practice of medicine and veterinary science that instruments inserted into the body should have a low coefficient of friction between the instrument and surrounding tissues to facilitate ease of insertion and also to minimize trauma to the tissues surrounding the insertion tract. In addition, guidewires are often used to facilitate insertion of several interventional medical instruments, such as catheters, stents, etc. Guidewires and interventional medical instruments are often coated with hydrophilic coatings that include a water soluble polymer. These hydrophilic polymers are lubricious coatings that are activated by contact with a wetting fluid, such as sterile water or saline, to provide a slippery surface when activated. Thus, hydrophilic coated guidewires and interventional medical instruments have a low coefficient of friction, provided that they are sufficiently wet.
A disadvantage of such hydrophilic coatings is the requirement that they be continuously wet to maintain their lubricity during use. Furthermore, if such a coated instrument is first wetted and then allowed to dry, the coated surface passes through a phase where the surface becomes somewhat tacky and has a much higher coefficient of friction as compared to the end phase when the coating has completely dried. It is therefore essential to ensure that those parts of the instrument which lie outside the body are wet immediately before insertion.
To maintaining sufficient wetness of a hydrophilic coated surface, it is currently necessary for a surgical assistant to keep the coated medical device (guidewire, catheter, etc.) wet while the physician manipulates the device. However, it is often difficult for a physician and an assistant to coordinate wetting and manipulation of the device during the procedure. Moreover, wiping such coated devices with wet gauze pads (as is often the case) can leave a residue which adheres to the surface of such devices.